start_sequence

        # Psych::TreeBuilder.start_sequence

(from ruby core)
### Implementation from Handler
---
    start_sequence(anchor, tag, implicit, style)

---

Called when a sequence is started.

`anchor` is the anchor associated with the sequence or nil. `tag` is the
tag associated with the sequence or nil. `implicit` a boolean indicating
whether or not the sequence was implicitly started. `style` is an
integer indicating the list style.

See the constants in Psych::Nodes::Sequence for the possible values of
`style`.

### Example

Here is a YAML document that exercises most of the possible ways this
method can be called:

    ---
    - !!seq [
      a
    ]
    - &pewpew
      - b

The above YAML document consists of three lists, an outer list that
contains two inner lists.  Here is a matrix of the parameters sent to
represent these lists:

    # anchor    tag                       implicit  style
    [nil,       nil,                      true,     1     ]
    [nil,       "tag:yaml.org,2002:seq",  false,    2     ]
    ["pewpew",  nil,                      true,     1     ]