This method builds a data frame representing the mutation.
Details
The data frame has the columns chr, chr_pos, ref, alt,
type (i.e., "SNV" and "indel"), and cause.
Examples
snv <- SNV("X", 20002, "T", "A")
snv$get_dataframe()
#> chr chr_pos allele ref alt type cause
#> 1 X 20002 random A T SNV <NA>
