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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _to_roman(num):
 """Convert integer to roman numerals."""

    roman_numeral_map = (
        ('M',  1000),
        ('CM', 900),
        ('D',  500),
        ('CD', 400),
        ('C',  100),
        ('XC', 90),
        ('L',  50),
        ('XL', 40),
        ('X',  10),
        ('IX', 9),
        ('V',  5),
        ('IV', 4),
        ('I',  1)
    )
    if not (0 < num < 5000):
        log(WARN, 'Number out of range for roman (must be 1..4999)')
        return str(num)
    result = ''
    for numeral, integer in roman_numeral_map:
        while num >= integer:
            result += numeral
            num -= integer
    return result