Function: equal

Return t if two Lisp objects have similar structure and contents.
They must have the same data type.
Conses are compared by comparing the cars and the cdrs.
Vectors and strings are compared element by element.
Numbers are compared by value, but integers cannot equal floats.
(Use `=' if you want integers and floats to be able to be equal.)
Symbols must match exactly. (fn O1 O2)