import proveit
from proveit import k, l, n, x
from proveit.numbers import Natural, NaturalPos
from proveit.numbers import zero, one
from proveit.logic import InSet
#from proveit.numbers.number_sets.integers import naturals_def
#from proveit.numbers.numerals.decimals import posnat1
from proveit.logic.booleans.quantification.universality import forall_in_bool
theory = proveit.Theory() # the theorem's theory
%proving nat_membership_is_bool
# naturals_def
# naturals_def_inst = naturals_def.instantiate({n:x, x:k})
# naturals_def_inst_rhs = naturals_def_inst.rhs
# naturals_def_inst_rhs__inbool = naturals_def_inst_rhs.deduce_in_bool()
# naturals_def_inst.sub_left_side_into(naturals_def_inst_rhs__inbool)
# %qed