Enforce a space in certain situations.

        There are cases where we will want a space where normally we
        wouldn't put one. This just enforces the addition of a space.

def _enforce_space(self, item):
        """Enforce a space in certain situations.

        There are cases where we will want a space where normally we
        wouldn't put one. This just enforces the addition of a space.

        """
        if isinstance(self._lines[-1],
                      (self._Space, self._LineBreak, self._Indent)):
            return

        if not self._prev_item:
            return

        item_text = unicode(item)
        prev_text = unicode(self._prev_item)

        # Prefer a space around a '.' in an import statement, and between the
        # 'import' and '('.
        if (
            (item_text == '.' and prev_text == 'from') or
            (item_text == 'import' and prev_text == '.') or
            (item_text == '(' and prev_text == 'import')
        ):
            self._lines.append(self._Space())