code: def clean_strings(iterable):
      
      retval = []
      for val in iterable:
          try:
              retval.append(val.strip())
          except(AttributeError):
              retval.append(val)
      return retval
docs: Take a list of strings and clear whitespace 
      on each one. If a value in the list is not a 
      string pass it through untouched.
  
      Args:
          iterable: mixed list
  
      Returns: 
          mixed list