def entities_spans(text, entity_re, abbrv_re):
    """
    Finds all the entities in the text, returning a list with every
    instance of the entity. If no entities are found, an empty list is
    returned.

    Args:
        text (str): text to search
        entity_re (SRE_Pattern): compiled regular expression
        abbrv_re (SRE_Pattern): compiled regular expression

    Returns:
        List[tuple]
    """
    ent_list = list()
    for mobj in entity_re.finditer(text):
        entity_span = (mobj.group(), (mobj.start(), mobj.end()))
        ent_list.append(entity_span)

    for mobj in abbrv_re.finditer(text):
        entity_span = (mobj.group(), (mobj.start(), mobj.end()))
        ent_list.append(entity_span)
    return ent_list