ber.go
func Unmarshal(b []byte, val interface{}) (rest []byte, err error) {
	return UnmarshalWithParams(b, val, "")
}
func Unmarshal(b []byte, val interface{}) (rest []byte, err error) {
	return UnmarshalWithParams(b, val, "")
}
// Unmarshal parses the BER-encoded ASN.1 data structure b
// and uses the reflect package to fill in an arbitrary value pointed at by val.
// Because Unmarshal uses the reflect package, the structs
// being written to must use upper case field names.
//
// An ASN.1 INTEGER can be written to an int, int32, int64,
// or *big.Int (from the math/big package).
// If the encoded value does not fit in the Go type,
// Unmarshal returns a parse error.
//
// An ASN.1 BIT STRING can be written to a BitString.
//
// An ASN.1 OCTET STRING can be written to a []byte.
//
// An ASN.1 OBJECT IDENTIFIER can be written to an
// ObjectIdentifier.
//
// An ASN.1 ENUMERATED can be written to an Enumerated.
//
// An ASN.1 UTCTIME or GENERALIZEDTIME can be written to a time.Time.
//
// An ASN.1 PrintableString or IA5String can be written to a string.
//
// Any of the above ASN.1 values can be written to an interface{}.
// The value stored in the interface has the corresponding Go type.
// For integers, that type is int64.
//
// An ASN.1 SEQUENCE OF x or SET OF x can be written
// to a slice if an x can be written to the slice's element type.
//
// An ASN.1 SEQUENCE or SET can be written to a struct
// if each of the elements in the sequence can be
// written to the corresponding element in the struct.
//
// The following tags on struct fields have special meaning to Unmarshal:
//
//	application	specifies that a APPLICATION tag is used
//	default:x	sets the default value for optional integer fields (only used if optional is also present)
//	explicit	specifies that an additional, explicit tag wraps the implicit one
//	optional	marks the field as ASN.1 OPTIONAL
//	set		causes a SET, rather than a SEQUENCE type to be expected
//	tag:x		specifies the ASN.1 tag number; implies ASN.1 CONTEXT SPECIFIC
//
// If the type of the first field of a structure is RawContent then the raw
// ASN1 contents of the struct will be stored in it.
//
// If the type name of a slice element ends with "SET" then it's treated as if
// the "set" tag was set on it. This can be used with nested slices where a
// struct tag cannot be given.
//
// Other ASN.1 types are not supported; if it encounters them,
// Unmarshal returns a parse error.