def confirm_lambda_psf(self):
    "Check whether a 'lambda_psf' value is needed, provide one"
    if ((self['PSFCOEFFS'] is not None) and (self['PSFRANGE'] is not None)):
        psf_range = self['PSFRANGE'].split()
        lambda_min = float(psf_range[0])
        lambda_max = float(psf_range[1])
        lambda_psf = (0.5 * (lambda_max + lambda_min))
    else:
        lambda_psf = None
    return lambda_psf
Check whether a 'lambda_psf' value is needed, provide one
def confirm_lambda_psf(self):
    
    if ((self['PSFCOEFFS'] is not None) and (self['PSFRANGE'] is not None)):
        psf_range = self['PSFRANGE'].split()
        lambda_min = float(psf_range[0])
        lambda_max = float(psf_range[1])
        lambda_psf = (0.5 * (lambda_max + lambda_min))
    else:
        lambda_psf = None
    return lambda_psf