Change stdlib imports to use std prefix in most examples (#17202)

lib/pure/collections/critbits.nim

@@ -13,7 +13,7 @@
 ## (A crit bit tree is a form of `radix tree`:idx: or `patricia trie`:idx:.)
 
 runnableExamples:
-  from sequtils import toSeq
+  from std/sequtils import toSeq
 
   var critbitAsSet: CritBitTree[void] = ["kitten", "puppy"].toCritBitTree
   doAssert critbitAsSet.len == 2
@@ -335,7 +335,7 @@ iterator leaves[T](n: Node[T]): Node[T] =
 iterator keys*[T](c: CritBitTree[T]): string =
   ## Yields all keys in lexicographical order.
   runnableExamples:
-    from sequtils import toSeq
+    from std/sequtils import toSeq
 
     let c = {"key1": 1, "key2": 2}.toCritBitTree
     doAssert toSeq(c.keys) == @["key1", "key2"]
@@ -349,7 +349,7 @@ iterator values*[T](c: CritBitTree[T]): T =
   ## **See also:**
   ## * `mvalues iterator <#mvalues.i,CritBitTree[T]>`_
   runnableExamples:
-    from sequtils import toSeq
+    from std/sequtils import toSeq
 
     let c = {"key1": 1, "key2": 2}.toCritBitTree
     doAssert toSeq(c.values) == @[1, 2]
@@ -375,7 +375,7 @@ iterator pairs*[T](c: CritBitTree[T]): tuple[key: string, val: T] =
   ## **See also:**
   ## * `mpairs iterator <#mpairs.i,CritBitTree[T]>`_
   runnableExamples:
-    from sequtils import toSeq
+    from std/sequtils import toSeq
 
     let c = {"key1": 1, "key2": 2}.toCritBitTree
     doAssert toSeq(c.pairs) == @[(key: "key1", val: 1), (key: "key2", val: 2)]
@@ -407,7 +407,7 @@ proc allprefixedAux[T](c: CritBitTree[T], key: string): Node[T] =
 iterator keysWithPrefix*[T](c: CritBitTree[T], prefix: string): string =
   ## Yields all keys starting with `prefix`.
   runnableExamples:
-    from sequtils import toSeq
+    from std/sequtils import toSeq
 
     let c = {"key1": 42, "key2": 43}.toCritBitTree
     doAssert toSeq(c.keysWithPrefix("key")) == @["key1", "key2"]
@@ -422,7 +422,7 @@ iterator valuesWithPrefix*[T](c: CritBitTree[T], prefix: string): T =
   ## **See also:**
   ## * `mvaluesWithPrefix iterator <#mvaluesWithPrefix.i,CritBitTree[T],string>`_
   runnableExamples:
-    from sequtils import toSeq
+    from std/sequtils import toSeq
 
     let c = {"key1": 42, "key2": 43}.toCritBitTree
     doAssert toSeq(c.valuesWithPrefix("key")) == @[42, 43]
@@ -451,7 +451,7 @@ iterator pairsWithPrefix*[T](c: CritBitTree[T],
   ## **See also:**
   ## * `mpairsWithPrefix iterator <#mpairsWithPrefix.i,CritBitTree[T],string>`_
   runnableExamples:
-    from sequtils import toSeq
+    from std/sequtils import toSeq
 
     let c = {"key1": 42, "key2": 43}.toCritBitTree
     doAssert toSeq(c.pairsWithPrefix("key")) == @[(key: "key1", val: 42), (key: "key2", val: 43)]

lib/pure/collections/deques.nim

@@ -200,7 +200,7 @@ iterator items*[T](deq: Deque[T]): T =
   ## **See also:**
   ## * `mitems iterator <#mitems,Deque[T]>`_
   runnableExamples:
-    from sequtils import toSeq
+    from std/sequtils import toSeq
 
     let a = [10, 20, 30, 40, 50].toDeque
     assert toSeq(a.items) == @[10, 20, 30, 40, 50]
@@ -230,7 +230,7 @@ iterator mitems*[T](deq: var Deque[T]): var T =
 iterator pairs*[T](deq: Deque[T]): tuple[key: int, val: T] =
   ## Yields every `(position, value)`-pair of `deq`.
   runnableExamples:
-    from sequtils import toSeq
+    from std/sequtils import toSeq
 
     let a = [10, 20, 30].toDeque
     assert toSeq(a.pairs) == @[(0, 10), (1, 20), (2, 30)]

lib/pure/collections/lists.nim

@@ -165,7 +165,7 @@ proc newSinglyLinkedNode*[T](value: T): <//>(SinglyLinkedNode[T]) =
 func toSinglyLinkedList*[T](elems: openArray[T]): SinglyLinkedList[T] {.since: (1, 5, 1).} =
   ## Creates a new `SinglyLinkedList` from members of `elems`.
   runnableExamples:
-    import sequtils
+    import std/sequtils
     let a = [1, 2, 3, 4, 5].toSinglyLinkedList
     assert a.toSeq == [1, 2, 3, 4, 5]
   result = initSinglyLinkedList[T]()
@@ -175,7 +175,7 @@ func toSinglyLinkedList*[T](elems: openArray[T]): SinglyLinkedList[T] {.since: (
 func toDoublyLinkedList*[T](elems: openArray[T]): DoublyLinkedList[T] {.since: (1, 5, 1).} =
   ## Creates a new `DoublyLinkedList` from members of `elems`.
   runnableExamples:
-    import sequtils
+    import std/sequtils
     let a = [1, 2, 3, 4, 5].toDoublyLinkedList
     assert a.toSeq == [1, 2, 3, 4, 5]
   result = initDoublyLinkedList[T]()
@@ -359,7 +359,7 @@ proc prepend*[T: SomeLinkedList](a: var T, b: T) {.since: (1, 5, 1).} =
   ## * `prependMoved proc <#prependMoved,DoublyLinkedList[T],DoublyLinkedList[T]>`_
   ##   for moving the second list instead of copying
   runnableExamples:
-    import sequtils
+    import std/sequtils
     var a = [4, 5].toSinglyLinkedList
     let b = [1, 2, 3].toSinglyLinkedList
     a.prepend b
@@ -476,7 +476,7 @@ proc prepend*[T](L: var SinglyLinkedList[T], value: T) {.inline.} =
 func copy*[T](a: SinglyLinkedList[T]): SinglyLinkedList[T] {.since: (1, 5, 1).} =
   ## Creates a shallow copy of `a`.
   runnableExamples:
-    import sequtils
+    import std/sequtils
     type Foo = ref object
       x: int
     var
@@ -675,7 +675,7 @@ proc add*[T: SomeLinkedList](a: var T, b: T) {.since: (1, 5, 1).} =
   ## * `addMoved proc <#addMoved,DoublyLinkedList[T],DoublyLinkedList[T]>`_
   ##   for moving the second list instead of copying
   runnableExamples:
-    import sequtils
+    import std/sequtils
     var a = [1, 2, 3].toSinglyLinkedList
     let b = [4, 5].toSinglyLinkedList
     a.add b

lib/pure/collections/sequtils.nim

@@ -39,7 +39,7 @@
 ## `method call syntax<manual.html#procedures-method-call-syntax>`_.
 
 runnableExamples:
-  import sugar
+  import std/sugar
 
   # Creating a sequence from 1 to 10, multiplying each member by 2,
   # keeping only the members which are not divisible by 6.
@@ -62,7 +62,7 @@ runnableExamples:
 
 
 runnableExamples:
-  from strutils import join
+  from std/strutils import join
 
   let
     vowels = @"aeiou"

lib/pure/collections/tables.nim

@@ -774,7 +774,7 @@ iterator allValues*[A, B](t: Table[A, B]; key: A): B {.deprecated:
   ## `add proc<#add,Table[A,B],A,sinkB>`_).
   ##
   runnableExamples:
-    import sequtils, algorithm
+    import std/[sequtils, algorithm]
 
     var a = {'a': 3, 'b': 5}.toTable
     for i in 1..3: a.add('z', 10*i)