Parses a string into a Variation.
The format for specifying variation settings follows. All valid CSS font-variation-settings values other than 'normal' and 'inherited' are also accepted, though, not documented below.
The format is a tag, optionally followed by an equals sign, followed by a number. For example `wght=500`, or `slnt=-7.5`.
| str |
a string to parse |
| variation |
the Variation to initialize with the parsed values |
| len |
length of |
|
`true` if |