<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _get_array(val, shape, default=None, dtype=np.float64):
 """Ensure an object is an array with the specified shape."""

    assert val is not None or default is not None
    if hasattr(val, '__len__') and len(val) == 0:  # pragma: no cover
        val = None
    # Do nothing if the array is already correct.
    if (isinstance(val, np.ndarray) and
            val.shape == shape and
            val.dtype == dtype):
        return val
    out = np.zeros(shape, dtype=dtype)
    # This solves `ValueError: could not broadcast input array from shape (n)
    # into shape (n, 1)`.
    if val is not None and isinstance(val, np.ndarray):
        if val.size == out.size:
            val = val.reshape(out.shape)
    out.flat[:] = val if val is not None else default
    assert out.shape == shape
    return out