code: def left_overlaps(self, other, min_overlap_size=1):
          
  
          if self.alt != other.alt:
              # allele must match!
              return False
  
          if len(other.prefix) > len(self.prefix):
              # only consider strings that overlap like:
              #   self: ppppAssss
              #   other:   ppAsssssss
              # which excludes cases where the other sequence has a longer
              # prefix
              return False
          elif len(other.suffix) < len(self.suffix):
              # similarly, we throw away cases where the other sequence is shorter
              # after the alt nucleotides than this sequence
              return False
  
          # is the other sequence a prefix of this sequence?
          # Example:
          # p1 a1 s1 = XXXXXXXX Y ZZZZZZ
          # p2 a2 s2 =       XX Y ZZZZZZZZZ
          # ...
          # then we can combine them into a longer sequence
          sequence_overlaps = (
              self.prefix.endswith(other.prefix) and
              other.suffix.startswith(self.suffix)
          )
          prefix_overlap_size = min(len(self.prefix), len(other.prefix))
          suffix_overlap_size = min(len(other.suffix), len(self.suffix))
          overlap_size = (
              prefix_overlap_size + suffix_overlap_size + len(self.alt))
  
          return sequence_overlaps and overlap_size >= min_overlap_size
docs: Does this VariantSequence overlap another on the left side?