<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def from_latlon(latitude, longitude, force_zone_number=None, force_zone_letter=None):
 """This function convert Latitude and Longitude to UTM coordinate Parameters latitude: float Latitude between 80 deg S and 84 deg N, e.g. (-80.0 to 84.0) longitude: float Longitude between 180 deg W and 180 deg E, e.g. (-180.0 to 180.0). force_zone number: int Zone Number is represented with global map numbers of an UTM Zone Numbers Map. You may force conversion including one UTM Zone Number. More information see utmzones [1]_ .. _[1]: http://www.jaworski.ca/utmzones.htm """

    if not in_bounds(latitude, -80.0, 84.0):
        raise OutOfRangeError('latitude out of range (must be between 80 deg S and 84 deg N)')
    if not in_bounds(longitude, -180.0, 180.0):
        raise OutOfRangeError('longitude out of range (must be between 180 deg W and 180 deg E)')
    if force_zone_number is not None:
        check_valid_zone(force_zone_number, force_zone_letter)

    lat_rad = mathlib.radians(latitude)
    lat_sin = mathlib.sin(lat_rad)
    lat_cos = mathlib.cos(lat_rad)

    lat_tan = lat_sin / lat_cos
    lat_tan2 = lat_tan * lat_tan
    lat_tan4 = lat_tan2 * lat_tan2

    if force_zone_number is None:
        zone_number = latlon_to_zone_number(latitude, longitude)
    else:
        zone_number = force_zone_number

    if force_zone_letter is None:
        zone_letter = latitude_to_zone_letter(latitude)
    else:
        zone_letter = force_zone_letter

    lon_rad = mathlib.radians(longitude)
    central_lon = zone_number_to_central_longitude(zone_number)
    central_lon_rad = mathlib.radians(central_lon)

    n = R / mathlib.sqrt(1 - E * lat_sin**2)
    c = E_P2 * lat_cos**2

    a = lat_cos * (lon_rad - central_lon_rad)
    a2 = a * a
    a3 = a2 * a
    a4 = a3 * a
    a5 = a4 * a
    a6 = a5 * a

    m = R * (M1 * lat_rad -
             M2 * mathlib.sin(2 * lat_rad) +
             M3 * mathlib.sin(4 * lat_rad) -
             M4 * mathlib.sin(6 * lat_rad))

    easting = K0 * n * (a +
                        a3 / 6 * (1 - lat_tan2 + c) +
                        a5 / 120 * (5 - 18 * lat_tan2 + lat_tan4 + 72 * c - 58 * E_P2)) + 500000

    northing = K0 * (m + n * lat_tan * (a2 / 2 +
                                        a4 / 24 * (5 - lat_tan2 + 9 * c + 4 * c**2) +
                                        a6 / 720 * (61 - 58 * lat_tan2 + lat_tan4 + 600 * c - 330 * E_P2)))

    if mixed_signs(latitude):
        raise ValueError("latitudes must all have the same sign")
    elif negative(latitude):
        northing += 10000000

    return easting, northing, zone_number, zone_letter