6.39.4  Getting the first element of a sequence or list: head

The head command finds the first element of a sequence or list.

• head takes one argument:
  S, a sequence or list.
• head(S) returns the first element of S.

Examples.

• Input:
  head(A,B,C,D)
  Output:

  A

• Input:
  head([0,1,2,3])
  Output:

  0