%
%	checktype rule checks argument`s data type which
%	would be an integer, float or list of integer or float.
%       Argument`s type can not be a string
%
checktype(X) :-	integer(X);float(X).
checktype(X) :-	string(X),write("Argument has incompatible type"),halt.
checktype([H|T]) :-checktype(H), checktype(T).
%
checkop(Expr, OpCode) :-
	string_codes(Expr, Es), 
	(	char_code('*', OpCode),	member(OpCode, Es) ->!;
		char_code('/', OpCode),	member(OpCode, Es) ->!;
		char_code('+', OpCode),	member(OpCode, Es) ->!;
		char_code('-', OpCode),	member(OpCode, Es) ->!;
		write("Operator does not found") 
	),!.

