def inplace_left_multiply_by(self, other: cirq.PAULI_STRING_LIKE) -> cirq.MutablePauliString:
        """Left-multiplies a pauli string into this pauli string.

        Args:
            other: A pauli string or `cirq.PAULI_STRING_LIKE` to left-multiply
                into `self`.

        Returns:
            The `self` mutable pauli string that was mutated.

        Raises:
            TypeError: `other` was not a `cirq.PAULI_STRING_LIKE`. `self`
                was not mutated.
        """
        if self._imul_helper_checkpoint(other, -1) is NotImplemented:
            raise TypeError(f"{other!r} is not cirq.PAULI_STRING_LIKE.")
        return self
Left-multiplies a pauli string into this pauli string.

        Args:
            other: A pauli string or `cirq.PAULI_STRING_LIKE` to left-multiply
                into `self`.

        Returns:
            The `self` mutable pauli string that was mutated.

        Raises:
            TypeError: `other` was not a `cirq.PAULI_STRING_LIKE`. `self`
                was not mutated.
        
cirq-core/cirq/ops/pauli_string.py