def aliases(self):
        """Returns a dictionary of the aliases, or "titles", of the field names
        in self. An alias can be specified by passing a tuple in the name
        part of the dtype. For example, if an array is created with
        ``dtype=[(('foo', 'bar'), float)]``, the array will have a field
        called `bar` that has alias `foo` that can be accessed using
        either `arr['foo']` or `arr['bar']`. Note that the first string
        in the dtype is the alias, the second the name. This function returns
        a dictionary in which the aliases are the keys and the names are the
        values. Only fields that have aliases are returned.
        """
        return dict(c[0] for c in self.dtype.descr if isinstance(c[0], tuple))