Add tasks for all the new languages

Task/Stack/Nim/stack.nim

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+import math
+
+type
+  EStackEmpty = object of E_Base
+
+  TStack* [A] = object
+    data: seq[A]
+    count: int
+
+proc initStack*[A](initialSize = 32): TStack[A] =
+  assert isPowerOfTwo(initialSize)
+  result.count = 0
+  newSeq(result.data,initialSize)
+
+proc cap*[A] (s: TStack[A]): int =
+  result = s.data.len
+
+proc len*[A](stack: TStack[A]): int =
+  result = stack.count
+
+proc push*[A](s: var TStack[A], item: A) =
+  if s.count == s.data.len:
+    # not enough room, make container bigger
+    var d: Seq[A]
+    newSeq(d,s.len * 2)
+    for i in 0 .. s.data.len - 1:
+      shallowCopy(d[i],s.data[i])
+    shallowCopy(s.data,d)
+  s.data[s.count] = item
+  inc(s.count)
+
+proc pop*[A](s: var TStack[A]): A {.raises: [EStackEmpty].}=
+  if s.count == 0:
+    raise newException(EStackEmpty,"the stack is empty")
+  dec(s.count)
+  result = s.data[s.count]
+
+proc top*[A](s: TStack[A]): A =
+  result = s.data[s.count - 1]
+
+proc isEmpty*[A](s: var TStack[A]): bool =
+  return s.count == 0
+
+#Tests
+when isMainModule:
+  var stk: TStack[char] = initStack[char](4)
+  stk.push('a')
+  stk.push('b')
+  stk.push('c')
+  stk.push('d')
+
+  assert(stk.count == 4)
+  assert(stk.data.len == 4)
+  stk.push('e')
+  assert(stk.cap == 8)
+  assert(stk.top == 'e')
+
+
+  discard stk.pop
+  discard stk.pop
+  discard stk.pop
+  discard stk.pop
+  assert(stk.isEmpty == false)
+  discard stk.pop
+  assert(stk.isEmpty == true)
+
+  try:
+    discard stk.pop
+  except:
+    let
+      e = getCurrentException()
+      msg = getCurrentExceptionMsg()
+    echo "Exception: [[", repr(e), "]] msg: ", msg