from typing import Sequence


def __express_list_of_sections(sections: Sequence[str]) -> str:
    """Convert list of sections into natural language.

    >>> __express_list_of_sections(["one"])
    'Section one'
    >>> __express_list_of_sections(["one", "two"])
    'Sections one and two'
    >>> __express_list_of_sections(["one", "two", "three"])
    'Sections one, two, and three'
    >>> __express_list_of_sections([])
    ''
    """
    if not sections:
        return ""
    sentence = "Section"
    if len(sections) == 1:
        sentence += " " + sections[0]
    else:
        sentence += "s "
        sentence += ", ".join(sections[:-1])
        if len(sections) > 2:
            sentence += ","
        sentence += " and " + sections[-1]
    return sentence