clear

        # IO::Buffer.clear

(from ruby core)
### Implementation from Buffer
---
    clear(value = 0, [offset, [length]]) -> self

---

Fill buffer with `value`, starting with `offset` and going for `length`
bytes.

    buffer = IO::Buffer.for('test')
    # =>
    #   <IO::Buffer 0x00007fca40087c38+4 SLICE>
    #   0x00000000  74 65 73 74         test

    buffer.clear
    # =>
    #   <IO::Buffer 0x00007fca40087c38+4 SLICE>
    #   0x00000000  00 00 00 00         ....

    buf.clear(1) # fill with 1
    # =>
    #   <IO::Buffer 0x00007fca40087c38+4 SLICE>
    #   0x00000000  01 01 01 01         ....

    buffer.clear(2, 1, 2) # fill with 2, starting from offset 1, for 2 bytes
    # =>
    #   <IO::Buffer 0x00007fca40087c38+4 SLICE>
    #   0x00000000  01 02 02 01         ....

    buffer.clear(2, 1) # fill with 2, starting from offset 1
    # =>
    #   <IO::Buffer 0x00007fca40087c38+4 SLICE>
    #   0x00000000  01 02 02 02         ....