<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _translate_category(glyph_name, unicode_category):
 """Return a translation from Unicode category letters to Glyphs categories."""

    DEFAULT_CATEGORIES = {
        None: ("Letter", None),
        "Cc": ("Separator", None),
        "Cf": ("Separator", "Format"),
        "Cn": ("Symbol", None),
        "Co": ("Letter", "Compatibility"),
        "Ll": ("Letter", "Lowercase"),
        "Lm": ("Letter", "Modifier"),
        "Lo": ("Letter", None),
        "Lt": ("Letter", "Uppercase"),
        "Lu": ("Letter", "Uppercase"),
        "Mc": ("Mark", "Spacing Combining"),
        "Me": ("Mark", "Enclosing"),
        "Mn": ("Mark", "Nonspacing"),
        "Nd": ("Number", "Decimal Digit"),
        "Nl": ("Number", None),
        "No": ("Number", "Decimal Digit"),
        "Pc": ("Punctuation", None),
        "Pd": ("Punctuation", "Dash"),
        "Pe": ("Punctuation", "Parenthesis"),
        "Pf": ("Punctuation", "Quote"),
        "Pi": ("Punctuation", "Quote"),
        "Po": ("Punctuation", None),
        "Ps": ("Punctuation", "Parenthesis"),
        "Sc": ("Symbol", "Currency"),
        "Sk": ("Mark", "Spacing"),
        "Sm": ("Symbol", "Math"),
        "So": ("Symbol", None),
        "Zl": ("Separator", None),
        "Zp": ("Separator", None),
        "Zs": ("Separator", "Space"),
    }

    glyphs_category = DEFAULT_CATEGORIES.get(unicode_category, ("Letter", None))

    # Exception: Something like "one_two" should be a (_, Ligature),
    # "acutecomb_brevecomb" should however stay (Mark, Nonspacing).
    if "_" in glyph_name and glyphs_category[0] != "Mark":
        return glyphs_category[0], "Ligature"

    return glyphs_category