Functional sequences can be subset using single or double brackets.
A single-bracket subset results in a new functional sequence, and
a double-bracket subset results in a single function.

# S3 method for fseq
[[(x, ...)
# S3 method for fseq
[(x, ...)

## Arguments

x |
A functional sequence |

... |
index/indices. For double brackets, the index must be of length 1. |

## Value

A function or functional sequence.