library displib 
-symbolic expression for eta to 3pi amplitude

library funclib
-numerical solutions for dispersive integrals contained in op6 amplitude¨

getting op
-pulling amplitude from displib

op2 op4 op6_fit
-fitting amplitude for KLOE data
- for symbolic reasons, in amplitude there is A_x, but order-wise there should
  be A_x/F_pi**2. For this reason you need to divide A_x from fits by F_pi**2
  to get value we wanted to fit for

NOTE
-displib doesnt work for newer versions of sympy than 1.18

-latest library versions the funclib was tested on
	-numpy 2.2.0
	-scipy 1.14.1
