Common concat_len_simple_equiv of type Equals

from the theory of proveit.core_expr_types

import proveit
# Automation is not needed when only building an expression:
proveit.defaults.automation = False # This will speed things up.
proveit.defaults.inline_pngs = False # Makes files smaller.
%load_expr # Load the stored expression as 'stored_expr'
# import the special expression
from proveit.core_expr_types import concat_len_simple_equiv

# check that the built expression is the same as the stored expression
assert concat_len_simple_equiv == stored_expr
assert concat_len_simple_equiv._style_id == stored_expr._style_id
print("Passed sanity check: concat_len_simple_equiv matches stored_expr")

Passed sanity check: concat_len_simple_equiv matches stored_expr

# Show the LaTeX representation of the expression for convenience if you need it.
print(stored_expr.latex())

\begin{array}{c} \begin{array}{l} |\left(a_{1}, a_{2}, \ldots, a_{i},f\left(1\right), f\left(2\right), \ldots, f\left(j\right)\right)| =  \\ \left(i + j\right) \end{array} \end{array}

stored_expr.style_options()

name	description	default	current value	related methods
operation	'infix' or 'function' style formatting	infix	infix
wrap_positions	position(s) at which wrapping is to occur; '2 n - 1' is after the nth operand, '2 n' is after the nth operation.	()	(2)	('with_wrapping_at', 'with_wrap_before_operator', 'with_wrap_after_operator', 'without_wrapping', 'wrap_positions')
justification	if any wrap positions are set, justify to the 'left', 'center', or 'right'	center	center	('with_justification',)
direction	Direction of the relation (normal or reversed)	normal	normal	('with_direction_reversed', 'is_reversed')

# display the expression information
stored_expr.expr_info()

	core type	sub-expressions	expression
0	Operation	operator: 1 operands: 2
1	Literal
2	ExprTuple	3, 4
3	Operation	operator: 5 operands: 6
4	Operation	operator: 7 operands: 8
5	Literal
6	ExprTuple	9, 10
7	Literal
8	ExprTuple	12, 15
9	ExprRange	lambda_map: 11 start_index: 14 end_index: 12
10	ExprRange	lambda_map: 13 start_index: 14 end_index: 15
11	Lambda	parameter: 21 body: 16
12	Variable
13	Lambda	parameter: 21 body: 17
14	Literal
15	Variable
16	IndexedVar	variable: 18 index: 21
17	Operation	operator: 19 operand: 21
18	Variable
19	Variable
20	ExprTuple	21
21	Variable