text: from sqlalchemy import ForeignKey, Column, String
  from sqlalchemy.ext.declarative import declarative_base
  from sqlalchemy.orm import relationship
  
  
  Base = declarative_base()
  
  
  class Skill(Base):
      __tablename__ = 'skills'
  
      id = Column(String, primary_key=True)
      name = Column(String)
      parent = Column(String, ForeignKey('skills.id'))
      parent_skill = relationship("Skill", remote_side=[id], uselist=False)
  