code: def flatten(iterable):
      
      if isiterable(iterable):
          flat = []
          for item in list(iterable):
              item = flatten(item)
              if not isiterable(item):
                  item = [item]
              flat += item
          return flat
      else:
          return iterable
docs: convenience tool to flatten any nested iterable
  
      example:
  
          flatten([[[],[4]],[[[5,[6,7, []]]]]])
          >>> [4, 5, 6, 7]
  
          flatten('hello')
          >>> 'hello'
  
      Parameters
      ----------
      iterable
  
      Returns
      -------
      flattened object