The command type(expr, form, int) returns true if type(expr, form) is true and wdegree(expr) = int; in other words, if expr is an int-form

The type form includes all expressions declared to be forms through defform, as well as any product or sum that contains at least one term of type form. A power is of type form if the base is of  type form.

The types const, scalar, and form are mutually exclusive.  Any expression can belong to at most one of these types.

This function is part of the difforms package and can only be used after performing with(difforms).