Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
What is the crystal structure for the formula yba 2 cu 3 o 7?

### Inputs:
table_name: table, columns: ['Formula', 'Notation', 'T c (K)', 'No. of Cu-O planes in unit cell', 'Crystal structure']

### Response:
SELECT Crystal structure FROM table WHERE Formula = YBa 2 Cu 3 O 7