On Feb 2, 6:40 pm, Baris Demir <demirba... at gmail.com> wrote: > def simpleCut(d=dict()): > temp=d > for i in temp.keys(): > if (temp[i] == .......) : > temp[i]=new_value > return temp You have been bitten by the shared default parameter noobie trap: http://www.python.org/doc/faq/general/#why-are-default-values-shared-between-objects