def find(pred, iterable):
    """
    Find the first occurrence of the predicate function returning true
    over the iterable; otherwise None.
    >>> find(lambda e: e.startswith('g'), ['alpha', 'beta', 'gamma', 'delta'])
    'gamma'
    >>> find(lambda e: e.startswith('p'), ['alpha', 'beta', 'gamma', 'delta'])
    None
    """

    for element in iterable:
        if pred(element):
            return element