code: func (t *TableMap) ColMap(field string) *ColumnMap {
  	col := colMapOrNil(t, field)
  	if col == nil {
  		e := fmt.Sprintf("No ColumnMap in table %s type %s with field %s",
  			t.TableName, t.gotype.Name(), field)
  
  		panic(e)
  	}
  	return col
  }
docs: // ColMap returns the ColumnMap pointer matching the given struct field
  // name.  It panics if the struct does not contain a field matching this
  // name.