def local_fehdist(feh):
fehdist= <NUM_LIT>/<NUM_LIT>*np.exp(-<NUM_LIT:0.5>*(feh-<NUM_LIT>)**<NUM_LIT>/<NUM_LIT>**<NUM_LIT>)+<NUM_LIT>/<NUM_LIT>*np.exp(-<NUM_LIT:0.5>*(feh+<NUM_LIT>)**<NUM_LIT>/<NUM_LIT>**<NUM_LIT>)<EOL>return fehdist<EOL>
feh PDF based on local SDSS distribution

    From Jo Bovy:
    https://github.com/jobovy/apogee/blob/master/apogee/util/__init__.py#L3
    2D gaussian fit based on Casagrande (2011)