for '[x] 23x + 567910 + 5'

I get
{'a': {'a': {'a': {'n': 6, 'op': 'imm'},
'b': {'n': 0, 'op': 'arg'},
'op': '*'},
'b': {'n': 18900, 'op': 'imm'},
'op': '+'},
'b': {'n': 5, 'op': 'imm'},
'op': '+'}

but it should be 18905..