def _validate(self):
if self.closed not in _VALID_CLOSED:<EOL><INDENT>raise ValueError("<STR_LIT>"<EOL>.format(closed=self.closed))<EOL><DEDENT>if len(self.left) != len(self.right):<EOL><INDENT>raise ValueError('<STR_LIT>')<EOL><DEDENT>left_mask = notna(self.left)<EOL>right_mask = notna(self.right)<EOL>if not (left_mask == right_mask).all():<EOL><INDENT>raise ValueError('<STR_LIT>'<EOL>'<STR_LIT>')<EOL><DEDENT>if not (self.left[left_mask] <= self.right[left_mask]).all():<EOL><INDENT>raise ValueError('<STR_LIT>')<EOL><DEDENT>
Verify that the IntervalArray is valid.

        Checks that

        * closed is valid
        * left and right match lengths
        * left and right have the same missing values
        * left is always below right