def make_fst(*custom_arcs: str, a_and_b='positive') -> FST:
"""
To make a complete FST, add one or more arcs that go from state 1 to state 2.
There are existing arcs to state 1 that set x <- a, set x <- b, and do not define x.
a_and_b can be either 'positive' for @P.x.V@ flags or 'unify' for @U.x.V@
flags.
"""
a_and_b_arcs = UNIFY_ARCS if a_and_b == 'unify' else POSITIVE_SET_ARCS
arcs = (ACCEPT_C, ACCEPTING_STATE, *a_and_b_arcs, *custom_arcs)
source = HEADER + '\n'.join(arcs) + FOOTER
return FST.from_text(source)
def english_flags_fst(english_flags_fst_txt: str) -> FST:
"""
Return the FST that uses flag diacritics and tranduces
pay/payable/unpayable/do/undo/doable/undoable.
"""
return FST.from_text(english_flags_fst_txt)
def eat_fst(eat_fst_txt: str) -> FST:
"""
Return the FST that analyzes eat/eats/eaten/eating/ate.
"""
return FST.from_text(eat_fst_txt)