pub fn num_rows(&self) -> usize {
        if self.columns.is_empty() {
            0
        } else {
            self.columns[0].len()
        }
    }
/// Get the number of rows in the chunk.
Get the number of rows in the chunk.
Get the number of rows in the chunk .
pub fn num_rows(&self) -> usize {
        if self.columns.is_empty() {
            0
        } else {
            self.columns[0].len()
        }
    }
pub fn num_rows ( & self ) -> usize { if self . columns . is_empty ( ) { 0 } else { self . columns [ 0 ] . len ( ) } }
Get the number of rows in the chunk.
Get the number of rows in the chunk .
&self