matches
Tries to match this expression with expr. The matching rules are: (i) a variable matches everything; (ii) a constant value matches an identical constant value; (iii) a number matches an identical number or an operator, (iv) operators match everything but constants, (v) comparators match numbers and operators (verifying the values); (vi) expr type can't be comparator; (vii) add and rem operators work only with lists.
Return
true if this expression can "match" with expr.
Parameters
expr
the expression to match
map
the matches map