code: def upgrade():
      op.create_table(
          "agent_skills",
          sa.Column("agent_id", sa.Integer(), nullable=False),
          sa.Column("skill_id", sa.Integer(), nullable=False),
          sa.PrimaryKeyConstraint("agent_id", "skill_id"),
      )
  
imports: from alembic import op
  import sqlalchemy
label_desc: Use image node_id 1 for calling a global function with example usage: upgrade() without return types