<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get_position(directory, identifier):
 """ Extracts the position of a paragraph from the identifier, and the parent directory of the paragraph. Parameters directory : Path A parent directory of a paragraph. identifier : str An identifier of a paragraph. Returns ------- float The estimated position of the paragraph in the range [0; 1). """

    paragraph_number = get_paragraph_number(identifier)
    paragraph_total = max(  # Not all paragraphs are stored, e.g. because of processing errors.
        get_paragraph_number(get_identifier(document)) + 1
        for document in directory.iterdir())
    assert paragraph_total > paragraph_number and paragraph_total > 0
    position = paragraph_number / paragraph_total
    return position