Stores a discrete character history, usually produced by reading in a file in
`simmap` format, or retrieving from a `dnPhyloCTMCDASiteIID` distribution.
Individual character histories can be accessed as follows:
- `char_hist[n]`: returns the `n`th character history.
# read character histories
char_hist = readCharacterHistory("simmap.tree")
# retrieve the first character history
first_char_hist = char_hist[1]