def find_key(key, obj):
    """
    Athena openx SerDe is case insensitive, and converts by default each object's key
    to a lowercase value: https://docs.aws.amazon.com/athena/latest/ug/json-serde.html

    Here we convert the DataMapper value for the column identifier
    (for instance, customerid) to the JSON's object key (for instance, customerId).
    """
    if not obj:
        return None
    for found_key in obj.keys():
        if key.lower() == found_key.lower():
            return found_key