def raise_on_type_mismatch number
      raise ArgumentError unless number.is_a?(Integer) or number.is_a?(String)
    end
def raise_on_type_mismatch number
      raise ArgumentError unless number.is_a?(Integer) or number.is_a?(String)
    end
Checks input type and raises if requirement is not met (currently the value has to be an integer)
 @param  number [Object]