Function variant_get 

pub fn variant_get(
    input: &Arc<dyn Array>,
    options: GetOptions<'_>,
) -> Result<Arc<dyn Array>, ArrowError>

Returns an array with the specified path extracted from the variant values.

The return array type depends on the as_type field of the options parameter

1. as_type: None: a VariantArray is returned. The values in this new VariantArray will point to the specified path.
2. as_type: Some(<specific field>): an array of the specified type is returned.

Casting Semantics

Scalar conversion semantics intentionally follow Arrow cast behavior where applicable. Conversions in this module delegate to Arrow compute cast helpers such as num_cast, cast_num_to_bool, single_bool_to_numeric, and cast_single_string_to_boolean_default.

• Getting DataType::Boolean accepts boolean, numeric, and string variants. Numeric zero maps to false; non-zero maps to true. String parsing follows Arrow UTF8-to-boolean cast rules.
• Getting numeric datatypes such as DataType::Int8, DataType::Int16, DataType::Int32, DataType::Int64, DataType::UInt8, DataType::UInt16, DataType::UInt32, DataType::UInt64, DataType::Float16, DataType::Float32, DataType::Float64 accept boolean and numeric variants (integers, floating-point, and decimals). They return None when conversion is not possible.
• Getting decimals such as DataType::Decimal32, DataType::Decimal64, DataType::Decimal128, DataType::Decimal256 accept compatible decimal variants, integer variants, float variants and string variants. They return None when conversion is not possible.

TODO: How would a caller request a struct or list type where the fields/elements can be any variant? Caller can pass None as the requested type to fetch a specific path, but it would quickly become annoying (and inefficient) to call variant_get for each leaf value in a struct or list and then try to assemble the results.