message: Simplify Dataset::{shape,ndims}
diff: @@ -55,20 +55,12 @@ impl Location for Dataset {}
  impl Dataset {
  /// Returns the shape of the dataset.
  pub fn shape(&self) -> Vec<Ix> {
  - if let Ok(s) = self.dataspace() {
  - s.dims()
  - } else {
  - vec![]
  - }
  + self.dataspace().ok().map_or_else(Vec::new, |s| s.dims())
  }
  /// Returns the number of dimensions in the dataset.
  pub fn ndim(&self) -> usize {
  - if let Ok(s) = self.dataspace() {
  - s.ndim()
  - } else {
  - 0
  - }
  + self.dataspace().ok().map_or(0, |s| s.ndim())
  }
  /// Returns the total number of elements in the dataset.
  