public void removeColumn(Column c){
  int idx=m_columns.indexOf(c);
  if (idx < 0) {
    throw new IllegalArgumentException("No such column.");
  }
  removeColumn(idx);
}

public void removeColumn ( Column c ) { int idx = m_columns . indexOf ( c ) ; if ( idx < 0 ) { throw new IllegalArgumentException ( "No such column." ) ; } removeColumn ( idx ) ; }
remove a column from this table
