[SQLObject] removing a unique constraint

[Timothy W. G. <tim...@si...>]

I have a table in an sqlite database that was created using the 
following class:

class Sentence(SQLObject):
     video = UnicodeCol(alternateID=True, default="", unique=True)
     lang1 = UnicodeCol(default="", unique=True)
     lang2 = UnicodeCol(default="")

I now would like to remove the unique constraint on the 'lang1' column. 
How would I do this? Thanks.

Best regards,
Tim