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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 is_merc_projection(srs):
 """ Return true if the map projection matches that used by VEarth, Google, OSM, etc. Is currently necessary for zoom-level shorthand for scale-denominator. """

    if srs.lower() == '+init=epsg:900913':
        return True

    # observed
    srs = dict([p.split('=') for p in srs.split() if '=' in p])
    
    # expected
    # note, common optional modifiers like +no_defs, +over, and +wkt
    # are not pairs and should not prevent matching
    gym = '+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null'
    gym = dict([p.split('=') for p in gym.split() if '=' in p])
        
    for p in gym:
        if srs.get(p, None) != gym.get(p, None):
            return False

    return True