<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def junctions(self):
 """Can be inferred from the exons, this is not implemented yet"""

    if len(self.exons) < 2: return []
    junctions = []
    for i in range(1,len(self.exons)):
      junctions.append(Junction(self.exons[i-1],self.exons[i]))
    return junctions