fn find_layer_with_fewest_0s(&self) -> usize {
        let layers = self.0.len();
        let height = self[0].len();
        let width  = self[0][0].len();
        let mut layer_with_fewest_0s = 0;
        let mut count_min = usize::max_value();
        for layer in 0..layers {
            let mut count_0s = 0;
            for row in 0..height {
                for column in 0..width {
                    if 0 == self[layer][row][column] {
                        count_0s += 1;
                    }
                }
            }
            if count_0s < count_min {
                count_min = count_0s;
                layer_with_fewest_0s = layer;
            }
        }
        layer_with_fewest_0s
        /*self.0.iter().fold(0, |count_min, layer| {
            // Count the 0s in this layer.
            let count_0s = layer.iter().fold(0, |acc, row| {
                acc + row.iter().fold(0, |acc, &elem| {
                    if 0 == elem {
                        acc + 1
                    } else {
                        acc
                    }
                })
            });
            // If there were fewer 0s in this layer,
            if count_0s < count_min {
                layer
            } else {
                
            }
        })*/
    }
// Find the layer which contains the lowest count of `0` digits.
Find the layer which contains the lowest count of `0` digits.
Find the layer which contains the lowest count of ` 0 ` digits .
fn find_layer_with_fewest_0s(&self) -> usize {
        let layers = self.0.len();
        let height = self[0].len();
        let width  = self[0][0].len();
        let mut layer_with_fewest_0s = 0;
        let mut count_min = usize::max_value();
        for layer in 0..layers {
            let mut count_0s = 0;
            for row in 0..height {
                for column in 0..width {
                    if 0 == self[layer][row][column] {
                        count_0s += 1;
                    }
                }
            }
            if count_0s < count_min {
                count_min = count_0s;
                layer_with_fewest_0s = layer;
            }
        }
        layer_with_fewest_0s
        /*self.0.iter().fold(0, |count_min, layer| {
            // Count the 0s in this layer.
            let count_0s = layer.iter().fold(0, |acc, row| {
                acc + row.iter().fold(0, |acc, &elem| {
                    if 0 == elem {
                        acc + 1
                    } else {
                        acc
                    }
                })
            });
            // If there were fewer 0s in this layer,
            if count_0s < count_min {
                layer
            } else {
            }
        })*/
    }
fn find_layer_with_fewest_0s ( & self ) -> usize { let layers = self . 0 . len ( ) ; let height = self [ 0 ] . len ( ) ; let width = self [ 0 ] [ 0 ] . len ( ) ; let mut layer_with_fewest_0s = 0 ; let mut count_min = usize :: max_value ( ) ; for layer in 0 .. layers { let mut count_0s = 0 ; for row in 0 .. height { for column in 0 .. width { if 0 == self [ layer ] [ row ] [ column ] { count_0s += 1 ; } } } if count_0s < count_min { count_min = count_0s ; layer_with_fewest_0s = layer ; } } layer_with_fewest_0s /*self.0.iter().fold(0, |count_min, layer| {
            // Count the 0s in this layer.
            let count_0s = layer.iter().fold(0, |acc, row| {
                acc + row.iter().fold(0, |acc, &elem| {
                    if 0 == elem {
                        acc + 1
                    } else {
                        acc
                    }
                })
            });
            // If there were fewer 0s in this layer,
            if count_0s < count_min {
                layer
            } else {
                
            }
        })*/ }
Find the layer which contains the lowest count of `0` digits.
Find the layer which contains the lowest count of ` 0 ` digits .
&self