trees.py
def is_leaf(self) -> bool:
        """ Return True if <self> has no children.

        Runtime: O(1)
        >>> tree = QuadTree((100, 100))
        >>> tree.is_leaf()
        True
        >>> tree.insert('a', (90, 90))
        >>> tree.is_leaf()
        True
        >>> tree.insert('b', (120, 120))
        >>> tree.is_leaf()
        False
        """
        return not self._ne and not self._se and not self._nw and not self._sw
 Return True if <self> has no children.

        Runtime: O(1)
        >>> tree = QuadTree((100, 100))
        >>> tree.is_leaf()
        True
        >>> tree.insert('a', (90, 90))
        >>> tree.is_leaf()
        True
        >>> tree.insert('b', (120, 120))
        >>> tree.is_leaf()
        False
        
Return True if  has no children.
Return True if has no children .
def is_leaf(self) -> bool:
        return not self._ne and not self._se and not self._nw and not self._sw
def is_leaf ( self ) -> bool : return not self . _ne and not self . _se and not self . _nw and not self . _sw
Return True if <self> has no children.
Return True if <self > has no children .
""" Return True if <self> has no children.

        Runtime: O(1)
        >>> tree = QuadTree((100, 100))
        >>> tree.is_leaf()
        True
        >>> tree.insert('a', (90, 90))
        >>> tree.is_leaf()
        True
        >>> tree.insert('b', (120, 120))
        >>> tree.is_leaf()
        False
        """
self