def _nt_obs_month
start_index = index
if node_cache[:obs_month].has_key?(index)
cached = node_cache[:obs_month][index]
if cached
cached = SyntaxNode.new(input, index...(index + 1)) if cached == true
@index = cached.interval.end
end
return cached
end
i0, s0 = index, []
r1 = _nt_CFWS
s0 << r1
if r1
r2 = _nt_month_name
s0 << r2
if r2
r3 = _nt_CFWS
s0 << r3
end
end
if s0.last
r0 = instantiate_node(SyntaxNode,input, i0...index, s0)
r0.extend(ObsMonth0)
else
@index = i0
r0 = nil
end
node_cache[:obs_month][start_index] = r0
r0
end