SYNOPSIS
        int m_contains(mixed &data1, ..., &dataN, map, key)

DESCRIPTION
        If the mapping contains the key map, the corresponding values
        are assigned to the data arguments, which must be passed by
        reference, and 1 is returned. If key is not in map, 0 is
        returned and the data args are left unchanged.
        It is possible to use this function for a 0-value mapping, in
        which case it has the same effect as member(E).

HISTORY
        Renamed from 'mapping_contains()' in LDMud 3.2.6.

SEE ALSO
        m_entry(E), mappings(LPC), member(E)