def Concatenate(sep=u','):
 def step(ctxt, value):
  if (value is not None):
   ctxt.append(value)
 def finalize(ctxt):
  if (not ctxt):
   return None
  return sep.join(ctxt)
 return ([], step, finalize)

def Concatenate ( sep = u',' ) : def step ( ctxt , value ) : if ( value is not None ) : ctxt . append ( value ) def finalize ( ctxt ) : if ( not ctxt ) : return None return sep . join ( ctxt ) return ( [ ] , step , finalize )
string concatenation aggregator for sqlite .