python - Writing the filter() function using for/while loops -

i trying understand how filter() function works , know how write:

test = filter(lambda x: x == y, lst)

using for or while loops.

filter() pretty making new list loop , conditional. in example, identical to:

l = [] in lst:     if == y:         l.append(i)

or list comprehension:

[i in lst if == y]

Shell