ParseTag parses the tags of the struct pointed to by structPtr.

Validation is a function that checks the validity of the struct pointer passed to it.

WriteToStruct is a function that takes a pointer to a struct and a function as arguments.

ErrNil is returned when the value is nil.

ErrNotPointer is returned when the value is not a pointer.

ErrNotStruct is returned when the value is not a struct.

StructFields represents a struct field and its associated tag.