def unique(input_list):
output = []<EOL>for item in input_list:<EOL><INDENT>if item not in output:<EOL><INDENT>output.append(item)<EOL><DEDENT><DEDENT>return output<EOL>
Return a list of unique items (similar to set functionality).

Parameters
----------
input_list : list
    A list containg some items that can occur more than once.

Returns
-------
list
    A list with only unique occurances of an item.