code: def increment(itr, n=1, format_msg="{}. "):
      
      for i, v in enumerate(itr, n):
          with prefix(format_msg, i):
              yield v
docs: Similar to enumerate but will set format_msg.format(n) into the prefix on
      each iteration
  
      :Example:
          for v in increment(["foo", "bar"]):
              echo.out(v) # 1. foo\n2. bar
  
      :param itr: iterator, any iterator you want to set a numeric prefix on on every
          iteration
      :param n: integer, the starting integer for the numeric prefix
      :param format_msg: string, this will basically do: format_msg.format(n) so there
          should only be one set of curly brackets
      :returns: yield generator