Function create_fastcover_dict_from_source 

pub fn create_fastcover_dict_from_source<R: Read, W: Write>(
    source: R,
    output: &mut W,
    dict_size: usize,
    fastcover: &FastCoverOptions,
    finalize: FinalizeOptions,
) -> Result<FastCoverTuned>

Available on crate feature dict_builder only.

Train and finalize a FastCOVER dictionary in pure Rust.

This function fully buffers the entire training corpus into memory via read_to_end, which can consume significant RAM for large inputs.