def __init__(self, device: cirq_google.GridDevice, start: GridQubit) -> None:
        """Greedy sequence search constructor.

        Args:
            device: Chip description.
            start: Starting qubit.

        Raises:
            ValueError: When start qubit is not part of a chip.
        """
        if start not in device.metadata.qubit_set:
            raise ValueError('Starting qubit must be a qubit on the chip')

        self._c = device.metadata.qubit_set
        self._c_adj = chip_as_adjacency_list(device)
        self._start = start
        self._sequence: list[GridQubit] | None = None
Greedy sequence search constructor.

        Args:
            device: Chip description.
            start: Starting qubit.

        Raises:
            ValueError: When start qubit is not part of a chip.
        
cirq-google/cirq_google/line/placement/greedy.py