ERROR: syntax error at or near ")" at character 20

-- no such operator

drop operator === (int4);

ERROR: argument type missing (use NONE for unary operators)

ERROR: missing argument

HINT: Use NONE to denote the missing argument of a unary operator.

-- no such operator by that name

drop operator === (int4, int4);

ERROR: operator does not exist: integer === integer

-- no such type1

drop operator = (nonesuch);

ERROR: argument type missing (use NONE for unary operators)

ERROR: missing argument

HINT: Use NONE to denote the missing argument of a unary operator.

-- no such type1

drop operator = ( , int4);

ERROR: syntax error at or near "," at character 19