code: def assert_is_lon(val):
      
      assert type(val) is float or type(val) is int, "Value must be a number"
      if val < -180.0 or val > 180.0:
          raise ValueError("Longitude value must be between -180 and 180")
docs: Checks it the given value is a feasible decimal longitude
  
      :param val: value to be checked
      :type val: int of float
      :returns:  `None`
      :raises: *ValueError* if value is out of longitude boundaries, *AssertionError* if type is wrong