def conditionally_calculate_md5(params, context, request_signer, **kwargs):
 if MD5_AVAILABLE:
  calculate_md5(params, **kwargs)

def conditionally_calculate_md5 ( params , context , request_signer , ** kwargs ) : if MD5_AVAILABLE : calculate_md5 ( params , ** kwargs )
only add a content-md5 if the system supports it .