Short: New efun: invert_mapping()
From: Tubmud
Type: Feature
See also: f-990203-22

SYNOPSIS
        inherit "basic/mapping";

        varargs mapping invert_mapping(mapping m, int dimension);

DESCRIPTION
        varargs mapping invert_mapping(mapping m, int dimension);
          This function returns a mapping where the keys are the former
          values of the given mapping m.
          Each value v is mapped to an array of those keys of m that
          m mapped to v.
          If m has more dimensions then you can also choose a different
          dimension of values to become the keys. The arrays will always
          contain the former keys, though.

=> Yup.

