def dedupe_list(l):
result = []<EOL>for el in l:<EOL><INDENT>if el not in result:<EOL><INDENT>result.append(el)<EOL><DEDENT><DEDENT>return result<EOL>
Remove duplicates from a list preserving the order.

    We might be tempted to use the list(set(l)) idiom, but it doesn't preserve
    the order, which hinders testability.