def extract_col_name(string):
    """
    Take a string and split it.
    String will be a format like "presence_pass_azimuth",
    where "azimuth" is the MagIC column name and "presence_pass"
    is the validation.
    Return "presence", "azimuth".
    """
    prefixes = ['presence_pass_', 'value_pass_', 'type_pass_']
    end = string.rfind('_')
    for prefix in prefixes:
        if string.startswith(prefix):
            return prefix[:-6], string[len(prefix):end]
    return string, string
