code: function(df) {
           return {
              d: function(x, logp) { return dt(df, logp)(x); },
              p: function(q, lowerTail, logp) {
                 return pt(df, lowerTail, logp)(q);
              },
              q: function(p, lowerTail, logp) {
                 return qt(df, lowerTail, logp)(p);
              },
              r: function() { return rt(df)(); }
           };
        }
docs: Returns an object representing a t distribution with $\textrm{df} > 0$
  degrees of freedom, with properties `d`, `p`, `q`, `r`.
  ```
  tdistr(a, b).d(x, logp)            // same as dt(a, b, logp)(x)
  tdistr(a, b).p(x, lowerTail, logp) // same as pt(a, b, lowerTail, logp)(x)
  tdistr(a, b).q(x, lowerTail, logp) // same as qt(a, b, lowerTail, logp)(x)
  tdistr(a, b).r()                   // same as rt(a, b)()
  ```
  @memberof t