functions are defined by def:

>>> def grow(a, b=[]):
...     b.append(a)
...     print b

S[:] makes a top-level copy of any sequence object; copy.deepcopy(X) makes full copies.

L[:0]=[X,Y,Z] inserts items at front of list L.

L[len(L):]=[X,Y,Z] and L.extend([X,Y,Z]) insert items at end (like in-place "+").

L.append(X) and X=L.pop( ) can be used to implement in-place stack operations.

Use for key in D.keys( ): to iterate through dictionaries, or simply for key in D: in 2.2.

Use K=D.keys( ); K.sort( ); for key in K: for ordered dictionary iteration.

X=A or B or None assigns X to the first true object among A and B, or None if both are false (i.e., 0 or empty).

X,Y = Y,X swaps the values of X and Y.

red, green, blue = range(3) assigns integer series.

Use try/finally statements to ensure that termination code is run.