code: def base0_interval_for_variant(variant):
      
      base1_location, ref, alt = trim_variant(variant)
      return base0_interval_for_variant_fields(
          base1_location=base1_location,
          ref=ref,
          alt=alt)
docs: Inteval of interbase offsets of the affected reference positions for a
      particular variant.
  
      Parameters
      ----------
      variant : varcode.Variant
  
      Returns triplet of (base1_location, ref, alt)