BytesReader wraps the Bytes method, usually implemented by bytes.Buffer, and an io.Reader.
Chain is an ordered processing chain. The next transform operation will receive the output from the previous.
New creates a content transformer chain given the provided transform funcs.
NewEmpty creates a new slice of transformers with a capacity of 20.
Apply passes the given from io.Reader through the transformation chain. The result is written to to.
FromTo is sent to each transformation step in the chain.
Transformer is the func that needs to be implemented by a transformation step.