Cover the base cases
if ( arr [ 0 ] == ' I ' ) : NEW_LINE INDENT v . append ( 1 ) NEW_LINE v . append ( 2 ) NEW_LINE min_avail = 3 NEW_LINE pos_of_I = 1 NEW_LINE DEDENT else : NEW_LINE INDENT v . append ( 2 ) NEW_LINE v . append ( 1 ) NEW_LINE min_avail = 3 NEW_LINE pos_of_I = 0 NEW_LINE DEDENT