gh-35686: fixing a lot of pycostyle warnings in calculus folder

    
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### 📚 Description

This is fixing a lot of pycodestyle warnings in the `calculus` folder,
in particular in `desolvers.py`.

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URL: #35686
Reported by: Frédéric Chapoton
Reviewer(s): Matthias Köppe

src/sage/calculus/all.py

@@ -1,34 +1,34 @@
 
 from .calculus import maxima as maxima_calculus
 from .calculus import (laplace, inverse_laplace,
-                      limit, lim)
+                       limit, lim)
 
 from .integration import numerical_integral, monte_carlo_integral
 integral_numerical = numerical_integral
 
 from .interpolation import spline, Spline
 
 from .functional import (diff, derivative,
-                        expand,
-                        taylor, simplify)
+                         expand,
+                         taylor, simplify)
 
-from .functions import (wronskian,jacobian)
+from .functions import (wronskian, jacobian)
 
 from .ode import ode_solver, ode_system
 
 from .desolvers import (desolve, desolve_laplace, desolve_system,
-                       eulers_method, eulers_method_2x2,
-                       eulers_method_2x2_plot, desolve_rk4, desolve_system_rk4,
-                       desolve_odeint, desolve_mintides, desolve_tides_mpfr)
+                        eulers_method, eulers_method_2x2,
+                        eulers_method_2x2_plot, desolve_rk4, desolve_system_rk4,
+                        desolve_odeint, desolve_mintides, desolve_tides_mpfr)
 
 from .var import (var, function, clear_vars)
 
 from .transforms.all import *
 
 # We lazy_import the following modules since they import numpy which slows down sage startup
 from sage.misc.lazy_import import lazy_import
-lazy_import("sage.calculus.riemann",["Riemann_Map"])
-lazy_import("sage.calculus.interpolators",["polygon_spline","complex_cubic_spline"])
+lazy_import("sage.calculus.riemann", ["Riemann_Map"])
+lazy_import("sage.calculus.interpolators", ["polygon_spline", "complex_cubic_spline"])
 
 from sage.modules.free_module_element import vector
 from sage.matrix.constructor import matrix
@@ -77,21 +77,21 @@ def symbolic_expression(x):
 
     If ``x`` is a list or tuple, create a vector of symbolic expressions::
 
-        sage: v=symbolic_expression([x,1]); v
+        sage: v = symbolic_expression([x,1]); v
         (x, 1)
         sage: v.base_ring()
         Symbolic Ring
-        sage: v=symbolic_expression((x,1)); v
+        sage: v = symbolic_expression((x,1)); v
         (x, 1)
         sage: v.base_ring()
         Symbolic Ring
-        sage: v=symbolic_expression((3,1)); v
+        sage: v = symbolic_expression((3,1)); v
         (3, 1)
         sage: v.base_ring()
         Symbolic Ring
         sage: E = EllipticCurve('15a'); E
         Elliptic Curve defined by y^2 + x*y + y = x^3 + x^2 - 10*x - 10 over Rational Field
-        sage: v=symbolic_expression([E,E]); v
+        sage: v = symbolic_expression([E,E]); v
         (x*y + y^2 + y == x^3 + x^2 - 10*x - 10, x*y + y^2 + y == x^3 + x^2 - 10*x - 10)
         sage: v.base_ring()
         Symbolic Ring
@@ -229,4 +229,5 @@ def symbolic_expression(x):
                     return SR(result).function(*vars)
     return SR(x)
 
+
 from . import desolvers

src/sage/calculus/calculus.py

@@ -2115,6 +2115,7 @@ def dummy_pochhammer(*args):
     from sage.functions.gamma import gamma
     return gamma(x + y) / gamma(x)
 
+
 #######################################################
 #
 # Helper functions for printing latex expression