Create a mask of which modes of the system are acted on by which terms.

fermion_term_list (list of FermionOperators): A list of fermionic terms to calculate the bitmask for. n_qubits (int): The number of qubits (modes) in the system. If not specified, defaults to the maximum of any term in fermion_term_list.

An n_qubits x len(fermion_term_list) boolean numpy array of whether each term acts on the given mode index.

ValueError if n_qubits is too small for the given terms.