================================================================================
Root attribute
================================================================================
direction: value

--------------------------------------------------------------------------------

(source_file
  (attr_key) (attr_value)
)

================================================================================
Inline shape attribute
================================================================================
foo.shape: oval
foo.bar.baz.shape: oval

--------------------------------------------------------------------------------

(source_file
  (shape (identifier) (dot) (attr_key) (attr_value))
  (shape (identifier) (dot) (identifier) (dot) (identifier) (dot) (attr_key) (attr_value))
)

================================================================================
Inline style attribute
================================================================================
foo.style.opacity: 5

--------------------------------------------------------------------------------

(source_file
  (shape (identifier) (dot) (attr_key) (dot) (attr_key) (attr_value))
)

================================================================================
Block style attributes
================================================================================
foo.style: {
  opacity: 5

  fill: red;
}

--------------------------------------------------------------------------------

(source_file
  (shape
    (identifier) (dot) (attr_key)
    (block
      (attr_key) (attr_value)
      (attr_key) (attr_value)
    )
  )
)

================================================================================
Inline block style attributes
================================================================================
foo.style: { opacity: 5; fill: red; }
foo.style: { opacity: 5 }

--------------------------------------------------------------------------------

(source_file
  (shape
    (identifier) (dot) (attr_key)
    (block
      (attr_key) (attr_value)
      (attr_key) (attr_value)
    )
  )
  (shape
    (identifier) (dot) (attr_key)
    (block
      (attr_key) (attr_value)
    )
  )
)