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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def convert_to_qutip(expr, full_space=None, mapping=None):
 """Convert a QNET expression to a qutip object Args: expr: a QNET expression full_space (HilbertSpace):
 The Hilbert space in which `expr` is defined. If not given, ``expr.space`` is used. The Hilbert space must have a well-defined basis. mapping (dict):
 A mapping of any (sub-)expression to either a `quip.Qobj` directly, or to a callable that will convert the expression into a `qutip.Qobj`. Useful for e.g. supplying objects for symbols Raises: ValueError: if `expr` is not in `full_space`, or if `expr` cannot be converted. """

    if full_space is None:
        full_space = expr.space
    if not expr.space.is_tensor_factor_of(full_space):
        raise ValueError(
            "expr '%s' must be in full_space %s" % (expr, full_space))
    if full_space == TrivialSpace:
        raise AlgebraError(
            "Cannot convert object in TrivialSpace to qutip. "
            "You may pass a non-trivial `full_space`")
    if mapping is not None:
        if expr in mapping:
            ret = mapping[expr]
            if isinstance(ret, qutip.Qobj):
                return ret
            else:
                assert callable(ret)
                return ret(expr)
    if expr is IdentityOperator:
        local_spaces = full_space.local_factors
        if len(local_spaces) == 0:
            raise ValueError("full_space %s does not have local factors"
                             % full_space)
        else:
            return qutip.tensor(*[qutip.qeye(s.dimension)
                                  for s in local_spaces])
    elif expr is ZeroOperator:
        return qutip.tensor(
            *[qutip.Qobj(csr_matrix((s.dimension, s.dimension)))
              for s in full_space.local_factors]
        )
    elif isinstance(expr, LocalOperator):
        return _convert_local_operator_to_qutip(expr, full_space, mapping)
    elif (isinstance(expr, Operator) and isinstance(expr, Operation)):
        return _convert_operator_operation_to_qutip(expr, full_space, mapping)
    elif isinstance(expr, OperatorTrace):
        raise NotImplementedError('Cannot convert OperatorTrace to '
                                  'qutip')
        # actually, this is perfectly doable in principle, but requires a bit
        # of work
    elif isinstance(expr, State):
        return _convert_ket_to_qutip(expr, full_space, mapping)
    elif isinstance(expr, SuperOperator):
        return _convert_superoperator_to_qutip(expr, full_space, mapping)
    elif isinstance(expr, Operation):
        # This is assumed to be an Operation on states, as we have handled all
        # other Operations above. Eventually, a StateOperation should be
        # defined as a common superclass for the Operations in the state
        # algebra
        return _convert_state_operation_to_qutip(expr, full_space, mapping)
    elif isinstance(expr, SLH):
        # SLH object cannot be converted to a single qutip object, only to a
        # nested list of qutip object. That's why a separate routine
        # SLH_to_qutip exists
        raise ValueError("SLH objects can only be converted using "
                         "SLH_to_qutip routine")
    else:
        raise ValueError("Cannot convert '%s' of type %s"
                         % (str(expr), type(expr)))