function lexeme return wrong result

[shinux]

>>>lexeme('encumbered')
>>>['encumber', 'encumbers', 'encumberring', 'encumberred']

but the word encumber's past tense should be encumbered. also the word crossbreed's past tense should be crossbreed.

found that all words endswith eed return the wrong past tense.

[aurghob]

+1 here - I tried :

lexeme('leave') ['leave', 'leaves', 'leaving', 'leaved']

the past tense of 'leave' is left and not 'leaved' - I am trying to convert either leave to left or left to leave by using lexeme but it's not yielding the intended result - is there any other way I can convert leave to left?