You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: count.rs
    path of file: ./repos/fish-shell/src/builtins
    
    the code of the file until where you have to start completion: use super::prelude::*;

// How many bytes we read() at once.
// Since this is just for counting, it can be massive.
const COUNT_CHUNK_SIZE: usize = 512 * 256;

/// Implementation of the builtin count command, used to count the number of arguments sent to it.
pub fn count(_parser: &Parser, streams: 
    
pub fn count(_parser: &Parser, streams: &mut IoStreams, argv: &mut [&wstr]) -> Option<c_int> {
    // Always add the size of argv (minus 0, which is "count").
    // That means if you call `something | count a b c`, you'll get the count of something _plus 3_.
    let mut numargs = argv.len() - 1;

    // (silly variable for Arguments to do nothing with)
    let mut zero = 0;

    // Count the newlines coming in via stdin like `wc -l`.
    // This means excluding lines that don't end in a newline!
    numargs += Arguments::new(&[] as _, &mut zero, streams, COUNT_CHUNK_SIZE)
        // second is "want_newline" - whether the line ended in a newline
        .filter(|x| x.1)
        .count();

    streams.out.appendln(numargs.to_wstring());

    if numargs == 0 {
        return STATUS_CMD_ERROR;
    }
    STATUS_CMD_OK
}