pub fn drop(&mut self, col_header: &str) {
        match self.ics.iter().position(|h| h == col_header) {
            Some(index) => {
                self.data.remove(index);
                self.ics.remove(index);
            }
            None => panic!("Can't drop header '{}'", col_header),
        }
    }
Drop specific column by header

# Examples

```rust
extern crate peroxide;
use peroxide::fuga::*;

fn main() {
let a = Series::new(vec![1,2,3,4]);
let b = Series::new(vec![5,6,7,8]);

let mut df = DataFrame::new(vec![a.clone(), b]);
df.set_header(vec!["a", "b"]);

let mut dg = DataFrame::new(vec![a]);
dg.set_header(vec!["a"]);

df.drop("b");

assert_eq!(df, dg);
}
```
src/structure/dataframe.rs