start_document

        # Psych::Handler.start_document

(from ruby core)
### Implementation from Handler
---
    start_document(version, tag_directives, implicit)

---

Called when the document starts with the declared `version`,
`tag_directives`, if the document is `implicit`.

`version` will be an array of integers indicating the YAML version being
dealt with, `tag_directives` is a list of tuples indicating the prefix
and suffix of each tag, and `implicit` is a boolean indicating whether
the document is started implicitly.

### Example

Given the following YAML:

    %YAML 1.1
    %TAG ! tag:tenderlovemaking.com,2009:
    --- !squee

The parameters for start_document must be this:

    version         # => [1, 1]
    tag_directives  # => [["!", "tag:tenderlovemaking.com,2009:"]]
    implicit        # => false